function getAverage(arr) {
	var avg = 0;
	for(var i = 0; i < arr.length; i++){
		avg += arr[i];
	}
	avg /= arr.length;
	return avg;
}

function getVariance(arr) {
	var variance = 0;
	for(var i = 0; i < arr.length; i++){
		variance += Math.pow(arr[i] - getAverage(arr),2);
	}
	variance = 1/arr.length * variance;
	return variance;
}

function getStandardDeviation(arr) {
	var stdDev = Math.sqrt(getVariance(arr));
	return stdDev;
}
